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- Q WHHHHHWI Aug. 17, 1937. A. F. MULHARE 2,090,139

VARIABLE LINE SPACER ori inal Filed Sept. 50, 1919 QM" WWII "WIN Q.

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3 Mull fillll-lllllllllllllllllllllllL N HIIIIIIIIllllllllllllllllfi Patented Aug. 17, 1937 UNITE STATES Means VARIABLEVLINE SPACER Andrew F. Mulhare, Glenbrook, Conn.

Refiled for abandoned application Serial No.

327,560, September 30, 1919. This application July 7, 1934, Serial No. 734,187.

October 13, 1936 3 Claims.

In the operation of typewriters it is often desirable to adjust the position of the paper slightly forward or backward with respect to the striking point. To make this conveniently possible, typewriter platens are constructed to permit of temporarily disengaging the platen from the ratchet wheel by which it is normally driven in the operation of line spacing.

My present invention provides an improved and novel construction of platen having the above purpose in view, the principal advantages of which are simplicity and cheapness of construction combined with directness and certainty of operation. A further and important object of the invention is to provide a device of this general character which shall involve the use of few parts and to so dispose the same that the entire connecting and disconnecting means (except the end of the operating shaft and the operating knob) are quite invisible.

My invention is illustrated in a preferred form in the accompanying drawing, wherein Figure 1 is a front elevation of the platen and its support; Figure 2 is a cross-sectional view of the 5 same on the line 2-2 in Figure 1; Figure 3 is a longitudinal sectional View of one end of the same on the line 3-3 in Figure 2; Figure 4 is a cross sectional view on the line 5-4 in Figure 3; Figure 5 is a view similar to Figure 3, but showing 30 the position of parts when the platen is disengaged from its driving ratchet wheel; and Figure 6 is a cross sectional view of the device on the line 3-5 in Figure 5. i

The platen roller Ill with its covering H is of 35 the usual construction and is carried at its two extremities by two hubs l2, (only one being shown) these hubs bearing on and being fixed to a central shaft |3. This shaft i3 turns in bearings in the usual end supports l4, l5, and

40 it may be turned, together with the platen, by

means of hand wheels Hi and IT, as is well understood in this art.

At the left hand, or operating end, the hub |2 has an extension l8 so proportioned as to form a 45 chamber symmetrically disposed around the shaft as shown in Figures 3 and 5.

The driving ratchet wheel l9 fits snugly against the end of the platen and is also provided with an extension 20, the end of which closes down 50 upon the shaft so that the ratchet wheel can turn loosely upon the shaft. Within this extension 20 there is formed a chamber corresponding with the chamber within the extension I8, and facing the same, as shown in Figures 3 and 5.

55 At the left or operating end, the shaft I3 is Renewed made hollow to permit the insertion of the sliding operating rod 2|, carrying the knob 22 to be grasped by the fingers in manipulating the device. Surrounding the shaft l3 and snugly fitting the same, is a slightly tapering sleeve 23, so placed and proportioned as to be capable of sliding on the shaft i3 from the chamber i8 to the chamber 20 and back again across the plane of the toothed portion of the ratchet wheel Hi.

In order to accomplish the shifting of the sleeve 23 in this manner, the operating rod 2| is provided with a pin 24, extending through slots 25 in the hollow portion of the shaft l3 and having its ends fixed to the sleeve 23.

The toothed portion of the ratchet wheel l9 encloses a hollow space 26 within which are placed the means for producing at will the normal mechanical engagement between the ratchet wheel and the shaft and platen. These means preferably comprise symmetrically disposed dogs 21, 28, pivotally mounted on the hub i2 at 29, 3|], each made with a short arm to which is pivoted a brake shoe 3|, 32, fitting the interior 7 cylindrical surface of the ratchet wheel rim, as shown in Figures 4 and 6. Each of the dogs is also provided with a second and longer arm 33, 34, whose suitably shaped extremity rests against the surface of the tapering sleeve 23.

The operation of the device will now be clear. When the platen is to be disengaged from the ratchet wheel, the rod 2| will be pulled out and into the position shown in Figure 5. This will bring the narrowest part of the sleeve 23 opposite the arms 33 and 34 of the dogs 2i and 28 and will leave the dogs and the brake shoes 3|, 32, quite loose as shown in Figure 6. This action will disengage the efficient mechanical connection between the ratchet wheel 19 and the platen and shaft.

If, on the contrary, the rod 2| be pushed inward, as in Figure 3, the thickest part of the sleeve 23 is brought to bear upon the ends of the arms 33 and 34, forcing the same apart around their bearing pivots 29 and 30, and forcing the brake shoes 3|, 32 with a powerful leverage against the interior cylindrical surface of the ratchet wheel. This will restore the efficient mechanical connection between the ratchet wheel and the shaft and platen, and place the apparatus in condition to be operated by the line spacing ratchet in the usual manner.

Various changes may be made in the construction of my device without departing from the scope of my invention, and I do not limit myself to the details herein shown and described.

This application is a substitute for my previous application, Serial No. 327,560, filed September 30, 1919.

What is claimed is:

1. In a typewriter, a platen having a central shaft, a hub for the platen at one end having a bearing on and a fixed connection to said shaft, a hollow ratchet wheel placed against said hub and having a loose bearing on said shaft, said hub and said ratchet wheel each having oppositely facing hollow extensions forming a chamber concentric with said shaft, means within said hollow ratchet wheel for engaging and disengaging said ratchet wheel and hub, and means for operating said engaging and disengaging means comprising a tapered sleeve mounted on said shaft, and slidable longitudinally thereon to and from a position mainly within the hollow extension on said ratchet-wheel to and from a position mainly within said hollow extension on said hub.

2. A device of the character set forth in claim 1 hereof, in which said operating means further comprises a rod adapted and arranged to slide in and out of the end of the shaft and to move said sleeve positively in both directions, and a pin passing through a longitudinal slot in the shaft connecting said rod and; sleeve.

3. In a device of the character set forth in 'claim 1 hereof, said engaging means comprising two-armed levers pivotally mounted on said hub and housed within said hollow ratchet wheel, each lever having its longer arm bearing on said tapered sleeve and having on its shorter arm a friction shoe bearing upon an overhanging part of the ratchet wheel and pivotally attached to said shorter arm.

7 ANDREW F. MULI-IARE. 

